Forging presses



5 Sheets-Sheet f3 IKVBNTOZ. UBHN Fas-val 9.0mm: Cnnc, IM B'w-vmam *BMMJ. FOSTER ETAL FORGING PRESSES Jan. 18, 1966 Filed Nov. 14, 1962 Jan.18, 1966 .1. FOSTER ETAL FORGING PRESSES 3 Sheets-Sheet 2 Filed NOV. 14.1962 Jan- 18, 1966 J. FOSTER ETAL 3,229,496

FORGING PRES SES Filed Nov. 14. 1962 3 Sheets-Sheet 5 INVENTORS L/afm/@sz-5,2

United States Patent O 3,229,496 FORGING PRESSES John Foster and RonaldGrace, Openshaw, Manchester, England, assignors to B. de S. Massey &Sons Ltd., a corporation of Great Britain, Northern Ireland, and Isle ofMan Filed Nov. 14, 1962, Ser. No. 237,679 Claims priority, applicationGreat Britain, Nov. 1961, 40,792/61 13 Claims. (Cl. 72-429) Thisinvention concerns forging presses and in particular although notexclusively, forging presses adapted to operate at high speeds.

As is generally known forging presses consist basically of a frameworkwithin which is slidably mounted a ram, movement of which is derivedfrom an eccentric shaft mounted in bearings in the upper region of theframe. A bolster is located at the lower end of the frame. The ram andthe bolster are arranged to carry dies. The eccentric shaft of the presscarries at one end a driving gear wheel, or heavy flywheel and at theother end there may be a brake. The ram is connected to the eccentricshaft by means of a heavy connecting rod having, at the eccentric end abig end bearing and at the ram a little end bearing,

As will be appreciated the bearings in a forging press are subjected tovery high stresses during their working life and any slackness in thebearings results in sloppy working.

It will also be appreciated that when the pres-s is in operation thelower region of the big end bearing, and the upper regions of theeccentric bearings, together with `the lower region of the little endbearing of the connecting rod are subjected to very high forces aspressure is applied to a workpiece since the reaction in these parts isall in the upward direction.

`If there is any slackness in the bearings the result of the abovereaction is to cause the bearing surfaces to hammer together therebyincreasing the wear on the bearings and eventually causing breakdownthereof.

To counteract the above effect it has been the practice to attempt tomaintain an oil film on the bearings which will serve as a cushion butwhen some wear has occurred in the bearings this cushion is inadequateand rapid deterioration occurs.

In order to reduce loading on the bearings it has also been the practiceto balance the ram statically by means of an air cylinder and pistonwhich in effect, continuously applies a lifting force on the ram whichis equivalent to its weight.

It has been appreciated by the applicants that the greatest load isapplied to the bearings when the forging operation has reached its finalstage since in this case the flash thickness of the forging may only Lbeone sixteenth of an inch thick and the pressure is applied to theworkpiece with the connecting rod almost at bottom dead centre and thatat this point the rate of deceleration of the ram assembly is at amaximum and this deceleration in a high speed press may be substantiallyequal to g thus the upward force necessary to maintain bearing contact,taking into account the weight of the reciprocating parts themselves maybe substantially equal to 2g When there is wear in the bearings of knownpresses the ram strikes the forging, in effect freely, until allclearance in the bearings has been taken up and the full pressure isapplied to the workpiece by the eccentric. In terms lof time theinterval between the ram striking the blow freely and the full pressureon the work- 3,229,496 Patented Jan. 18, 1966 'ice piece applied by theeccentric is very small but the resultant effect on bearing life,heating of the dies and the chilling effect on the forging is large.This effect is very pronounced where the final forging stage isvirtually a coining operation because the forging is now effectivelyonly the thickness of the flash (the remaining thickness beingsubstantially catered for by the dies) and the ternperature of theforging has considerably reduced so that the flow characteristics of themetal have considerably changed from the first time pressure was appliedon a hot, thick, relatively easily flowing metal workpiece.

In practice the last stroke may only reduce the flash thickness by a fewthousandths of an inch and thus accurate control of the stroke isessential. This cannot be achieved if the bearings are Worn and theaction of the ram is sloppy.

It has been suggested that the ram could be in effect staticallyoverbalanced by the air cylinder arrangement so that, `assuming the ramhas a weight of six tons, it could be statically overbalanced by anadditional six tons but such a press would not be a practicalproposition because of the extra power that would be required to drivethe ram downwards and as a result, presses are not constructed in thisway.

A `further reason for not overbalancing the ram in the manner justsuggested lies in the fact that, in such an arrangement, should inchingbe required under certain circumstances, the rarn would rise and thusinching would be impossible.

The object of the present invention is to provide .a forging press inwhich the disadvantages above referred to are overcome, or at leastsubstantially overcome so that the stroke control can be accuratelycontrolled and wear in the bearings considerably reduced.

According to the present invention there is provided a forging press inwhich in addition to static balancing of the ram there i-s provideddynamic balancing of the ram and pre-loading of the eccentric bearings,the dynamic balancing being arranged to become operative just prior tothe application of pressure to the workpiece and to remain operativeuntil the pressure is relieved by the commencement of upward movement ofthe ram.

Preferably there is provided a dynamic balancing arrangement including aconnecting-rod connected to the ram and to a piston contained, forexample, in a pneumatic cylinder, the arrangement being such that theram is subjected to an upward force equivalent to its weight during themajor part of its downward travel, there being, adjacent to the lowerend of the cylinder a plurality of balancing fluid escape port-sarranged to allow for very free escape of balancing fluid during themajor portion of the downstroke of the ram, the ports being arranged tobe closed by the piston to prevent escape of balancing fluid during thelatter part of the downstroke of the ram whereby compression of thefluid, and consequent dynamic balancing of the ram is achieved.

Preferably the eccentric shaft is pre-loaded at each end by means of afluid cylinder, for example, a multi-piston cylinder, the piston orpistons thereof being attached by means of a single connecting rod to abearing cage for anti-friction race or races mounted upon the eccentricshaft.

In an alternative construction the eccentric shaft bearings arepre-loaded at each end by resilient means consisting of a pack of springdiscs, or a coil spring or the like, the resilient means being connectedto a bearing cage for anti-friction race or races mounted upon aneccentric shaft.

The invention will be described further, by Way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a part sectional View of part of a forging press made inaccordance with the invention,

FIG. 2 is a detail of part of the press shown in FIG. 1 and FIG. 3 is avdetail view of another part of the press shown in FIG. 1.

In the following description only those parts of a forging press whichrelate to the invention will be referred to.

Referring to FIG. l it will be seen that across the upper end of theside frames of a forging press is mounted an eccentric shaft 10, theshaft being mounted in Phosphor bronze bearings 11. In the centralregion of the eccentric shaft is formed an eccentric 12 upon which ismounted the end of a connecting rod 13 in which is provided a Phosphorbronze big-end bearing 14. The other end of the connecting rod 13 isprovided with a little end bearing 15 and carries the ram 16.

The eccentric shaft 10 is pre-loaded so that, at all times, it tends torun on the upper region of the Phosphor bronze bearings 11. There is inpractice, an oil lm between the bearings 11 and the eccentric shaft 10.

At the end of the eccentric shaft 10 upon which is mounted the combinedclutch and flywheel 17 and as shown in FIG. 2, there is provided aroundthe shaft 10 a pair ofl ball races 18. The ball races 1S are mounted inan annular carrier 19 to which are secured two connectors 20. Theconnectors 20 are spaced apart by a spacer ring 21. Between theconnectors 20 and above the eccentric shaft 10 is a link member 22. Theconnectors 20 and the link member 22 are bored to receive the connectorpin, generally indicated at 23, which is substantially cylindrical inshape but whose diameter has three barrel shaped sections 24 along itslength so that at the centre of the bore in the two connectors 20 andthe link member 22 the diameter of the connector pin is greater than atthe edges of the connectors 2i) and the link member 22 and is in factsubstantially the same diameter as the bore of the connectors 20 andlink member 22. The connector pin is held in position by the provisionof end plates 23a, secured to the outer faces of the connectors 20 toblank off the bores therein.

The link member 22 is connected to the piston rod 25 of an air cylinder26 having a number of spaced apart pistons 27 in tandem.

The arrangement above described with slight modifications as shown inFIG. 3 is also provided at the end of the eccentric shaft 10 whichcarries the usual brake 28 but since the load on this end of the shaft10 is substantially less than that at the clutch and flywheel end onlyone ball race 29 is provided. In this case the air cylinder 30 requiresfewer pistons 31. Since only one bearingA 29 is provided there is onlyone connector 32 and the connector pin 33 has only one barrel shapedsection 34. A link member 35 connects the connector 32 to the piston rod36 of the air cylinder 30.

The` reason for the connector pin 23 having the shape above describedlies in the fact that the loading on the bearings 18 at the flywheel endof the shaft 10 is to be evenly distributed and therefore by virtue ofthe rocking motion which can occur between the connectors 20 andthe linkmember 22 the total loading on the ball races 18 is automatically evenlydistributed on the ball races 18.

The construction above described is used in view of the high cost anddifficulty experienced in producing matched bearings which of course,could be used as an alternative to the ball races used if it were acommercial proposition.

In use, air is supplied to the air cylinders 26 and 30v at sufficientpressure to maintain the eccentric shaft 10 hard up against the upperregion of its Phosphor bronze bearings 11 during operation of the press.

The air cylinders 26 and 30 above referred to may be replaced byresilient means such as a coil spring or pack of spring washers or thelike and in this case mechanical loading of the spring or washers wouldbe provided.

In a further alternative hydraulic cylinders operated with oil could beused in place of the air cylinders 26 and 30.

The ram is balanced statically and dynamically by means of an aircylinder 37 having provided therein a connecting piston 38 which isconnected to a piston rod 39, the latter being itself connected to theram 16. Air at the required pressure is supplied to the air cylinder 37from an air chamber 41 by means of a conduit not shown.

In the lower region of the cylinder 37 is provided a ring of ports 40which communicate with the air charnber 41. The base of the cylinder 37is provided with a bypass valve 42 which also communicates with the airchamber 41. The by-pass valve 42 is normally closed but becomesoperative when inching of the ram is necessary, as will herein bereferred to.

In normal use of the press the air pressure in the air cylinder 37 issuch as statically to balance the ram 16 and for the major portion ofthe downward stroke of the ram 16 this pressure remains constant sinceair can escape through the ring of ports 40 to the air chamber 41 as thepiston 38 descends.

Towards the end of the stroke the piston 38 overruns the ring of ports40 and traps air in the cylinder 37. Continued downward movement of theram 16 and piston 38 compre-sses the air and effectively overbalancesthe ram 16 thereby causing any slackness in the big and small endbearings 14 and 15 of the connecting rod 13 to be taken up.

When the pressure is applied to the workpiece therefore there is nosloppiness in the bearings 11, 14 and 15 and a controlled blow isachieved. This is most important when final forging is taking place,since the full pressure on the workpiece is in effect taken for thepurpose, in many cases, of reducing the thickness of the forging by onlya few thousandths of an inch.

If, as is often the case in known arrangements, there is clearance inthe bearings, an initial blow is struck with the ram in effect fallingfreely, the full pressure on the workpiece only being effective when allthe clearance has been taken up.

It has in fact, been known for there to be suicient clearance in thebearings for the ram to be able to effect a heavy blow on the dies whenno forging was located therebetween.

In the press according to the above description, the tendency for wearto occur in the bearings is reduced because of the provision of thepre-loading arrangement and the ability dynamically to balance the ramjust before pressure is applied to the workpiece. Obviously wear willoccur but this is reduced substantially and in any event sloppiness inthe bearings is prevented by virtue of the pre-loading and balancing ofthe ram.

When inching of the ram is required by the by-pass valve 42 in the baseof the air cylinder 37 is opened, preferably automatically by operationof the inching control, and thus even when the ring of ports 40 has beenclosed, air can escape from the volume of the cylinder 37 below thepiston 38 through the valve 42. The result of the opening of the valve42 and the consequent escape of air from the cylinder 37 is thatinsuicient pressure is built up in the cylinder to hold the ram or causeit to rise ,as referred to herein, thus inching (i.e., slow, shortmovements of the ram) can be achieved.

Throughout the specification references have been made to the ring ofports being in the lower region of the air cylinder. It should beappreciated however, that the dynamic balancing is required when the ramis about to apply pressure to the workpiece so that if the forging isone which, when finished is relatively thick it is possible to arrangefor the ports to be located anywhere along the cylinder. However, sincethe cylinder length will be comparable with the length of stroke of theram 13 the ports 4G should always be in the lower half of the cylinderand thus the term lower region of the cylinder should be construed inthe light of this possibility.

We claim:

1. A forging press including a framework, a ram slidably mounted in theframework, an eccentric shaft mounted in the framework and attached tothe ram by means of a connecting rod, end bearings on the connecting rodfor said eccentric shaft and said ram, static and dynamic balancingmeans for said ram, said static and dynamic balancing means including acylinder, a piston in said cylinder, a connection between said cylinderand said ram, an operating fluid chamber, a connection between saidchamber and said cylinder whereby free escape of an operating iiuid isallowed over a proportion of movement of said piston and is thereafterprevented to achieve dynamic balancing, said dynamic balancing to becomeoperative just prior to the impingement of said ram on a workpiece andto remain operative until the commencement of an upward stroke of saidram.

2. A forging press including a framework, a ram slidably mounted in saidframework, an eccentric shaft mounted in the framework and attached tosaid ram by means of a connecting rod, end bearings on the connectingrod respectively for said eccentric shaft and said ram, a connecting-rodconnected to said ram, a cylinder, a chamber in open communication withsaid cylinder, a piston in said cylinder connected to saidlast-mentioned connecting-rod, a plurality of ports in said cylinder inthe lower region thereof arranged to allow free escape of uid from saidcylinder into said chamber during downward movement of said piston untilsaid piston overrides said ring of ports, the arrangement being such asto statically balance said ram until said ring of ports is overrun bysaid piston and thereafter dynamically balance said ram due tocompression of said fluid, cornpression of said iluid occurring duringthe latter stages of downward movement of said piston and being edectiveuntil said ports become uncovered by upward movement of said piston.

3. A forging press as set forth in claim 2 in which said cylinder issupplied with air as the balancing fluid.

4. A forging press as set forth in claim 2 in which said cylinder issupplied with hydraulic oil as the balancing fluid.

5. A forging press including a framework, a ram slidably mounted in saidframework, an eccentric shaft mounted in the framework and attached tosaid ram by means of a connecting rod, end bearings on the connectingrod respectively for said eccentric shaft and said ram, a connecting rodconnected to said ram, a cylinder, a chamber in open communication withthe cylinder, a piston in said cylinder connected to said last-mentionedconnecting-rod, a plurality of ports in said cylinder in the lowerregion thereof arranged to allow free escape of tluid from said cylinderinto said chamber during downward movement of said piston until saidpiston overrides said ring of ports, the arrangement being such as tostatically balance said ram until said ring of ports is overrun by saidpiston and thereafter dynamically balance said ram due to compression ofsaid fluid, compression of said uid occurring during the latter stagesof downward movement of said piston and being effective until said portsbecome uncovered by upward movement of said piston, said eccentric shaftbeing preloaded at each end.

6. A forging press including a framework, a ram slidably mounted in saidframework, an eccentric shaft mounted in the framework and attached tosaid ram by means of a connecting rod, end bearings on the connectingrod respectively for said eccentric shaft and said ram, a connecting rodconnected to said ram, a cylinder, a piston in said cylinder connectedto said last-mentioned connecting rod, a plurality of ports in saidcylinder in the lower region thereof arranged to allow free escape offluid from said cylinder during downward movement of said piston untilsaid piston overrides said ring of ports, the arrangement being such asto statically balance said ram until said ring of ports is overrun bysaid piston and thereafter dynamically balance said ram due tocompression of said fluid, compression of said iiuid occurring duringthe latter stages of downward movement of said piston and beingeffective until said ports become uncovered by upward movement of saidpiston, one end of said eccentric shaft being pre-loaded by means of amulti-piston cylinder, said pistons having a piston rod connected to apair of connecting rods, a pair of anti-friction bearings on saideccentric shaft, an annular cage for said anti-friction bearings, a linkmember connecting said last-mentioned connecting rods and said pistonrod, a connector pin through said connecting rods and said link memberand means for supplying pre-loading fluid to said cylinder.

7. A forging press as set forth in claim 6 in which said connecting pinis substantially cylindrical, there being three barrel shaped sectionsthereon, the diameter at the centre of each of said barrel shapedsections being substantially the same as the diameter of the bore insaid connecting rods and said link member through which said pinextends.

8. A forging press including a framework, a ram slidably mounted in saidframework, an eccentric shaft mounted in said framework and attached tosaid ram by means of a connecting rod, end bearings on the connectingrod respectively for said eccentric shaft and said ram, a connecting rodconnected to said ram, a cylinder, a piston in said cylinder connectedto said last-mentioned connecting rod, a plurality of ports in saidcylinder in the lower region thereof arranged to allow free escape ofiluid from said cylinder during downward movement of said piston untilsaid piston overrides said ring of ports, the arrangement being such asto statically balance said ram until said ring of ports is overrun bysaid piston and thereafter dynamically balance said ram due tocompression of said uid, compression of said uid occurring during thelatter stages of downward movement of said piston, and being effectiveuntil said ports become uncovered by upward movement of said piston, oneend of said eccentric shaft being pre-loaded by means of a multi-pistoncylinder, said pistons having a piston rod connected to a pair ofconnecting rods, a pair of anti-friction bearings on said eccentricshaft, an annular cage for said anti-friction bearings, a link memberconnecting said connecting rods and said piston rod, a connector pinthrough said connecting rods and said link member and means forsupplying pre-loading iiuid to said cylinder, the other end of saideccentric shaft being preloaded by means of a cylinder, a piston in saidcylinder having a piston rod connected to a connecting rod, ananti-friction bearing on said eccentric shaft, an annular cage for saidanti-friction bearing, a link member connecting said connecting rod tosaid piston rod, a connector pin through said connecting rod and saidlink member and means for supplying pre-loading fluid to said cylinder.

9. A forging press as set forth in claim 8 in which said connecting pinpassing through said single connecting rod and said link member issubstantially cylindrical there being one barrel shaped section on saidconnecting pin the diameter of which at the centre of the barrel issubstantially equal to the diameter of a bore in said connecting rod.

10. A forging press as set forth in claim 8 in which said pre-loadingfluid is air.

References Cited by the Examiner UNITED STATES PATENTS Bassett 308-184Criley 10-15 Reed 78-42 Friedman 10-15 CHARLES W. LANHAM, PrimaryExaminer.

10 WILLIAM J. STEPHENSON, Examiner.

1. A FORGING PRESS INCLUDING A FRAMEWORK, A RAM SLIDABLY MOUNTED IN THEFRAMEWORK, AN ECCENTRIC SHAFT MOUNTED IN THE FRAMEWORK AND ATTACHED TOTHE RAM BY MEANS OF A CONNECTING ROD, END BEARINGS ON THE CONNECTING RODFOR SAID ECCENTRIC SHAFT AND SAID RAM, STATIC AND DYNAMIC BALANCINGMEANS FOR SAID RAM, SAID STATIC AND DYNAMIC BALANCING MEANS INCLUDING ACYLINDER, A PISTON IN SAID CYLINDER, A CONNECTION BETWEEN SAID CYLINDERAND SAID RAM, AN OPERATING FLUID CHAMBER, A CONNECTION BETWEEN SAIDCHAMBER AND SAID CYLINDER WHEREBY FREE ESCAPE OF AN OPERATING FLUID ISALLOWED OVER A PROPORTION OF MOVEMENT OF SAID PISTON AND IS THEREAFTERPREVENTED